Borrowed from Catalan dall or Occitan dalh, from Late Latin daculum (“sickle, scythe”), possibly from Proto-Indo-European *dʰalg-tlā, from *dʰalg-, *dʰalk- (“pricking, stabbing, or cutting tool; needle, pin; knife”), from *dʰelg-, *dʰelk- (“to stick, prick, stab”).
See also Lithuanian dilgėlė (“nettle”), dilgus (“prickly”), Latin falx (“hook, sickle”), Old Irish delg (“spine, needle”).